Not sure what could go wrong. Tested it with multiple keys (most recent SKSE/TESV.exe) and it works as intended every time. Are you sure you're pressing and holding the key i time, like start holding it while the load screen is still showing if it's already set. If it's not yet been set, just hold any key for 3-5 seconds tops and it should register as your blood options hotkey.

dcotton6871: The hotkey, initially, is undefined. Try 'Space' and just hold it until the menu pops. When loading any save after a key is selected, if said key is held while the save is loading, the menu will be prompted again. It's set up like this so it'll work for non-US keyboards as the DXScanCodes differ among keyboard layouts.

dcotton6871 : When the mod first loads, you should see a prompt in the upper left to press and hold your desired hotkey. Once it's selected, you'll be shown the menu. For revisiting the menu, save, then press and hold whatever key you had selected as the save loads.